(1) Field of the Invention
This invention generally relates to a launch tube assembly with an adjustable plenum volume.
More particularly, the invention relates to an adjustable length launch tube assembly with an adjustable plenum volume which assures that countermeasures launched from a launch tube have a predetermined acceleration.
(2) Description of the Prior Art
Current externally housed submarine countermeasures are launched by way of gas generators. The generated gas pressure builds up behind the ram plate and countermeasure until there is enough pressure to shear pins holding a muzzle cap in place. This then allows the countermeasure to move through the launch tube and exit. The current gas generator imparts acceleration to the device on the order of 90 g's. A redesign of the gas generator is expected to impart accelerations on the order of 50 g's.
The following patents, for example, disclose gas generation in launch systems, but do not disclose an adjustable length launch tube which in turn creates a predetermined initial plenum volume.                U.S. Pat. No. 5,819,526 to Jackson et al.;        U.S. Pat. No. 5,837,919 to Yagla et al.;        U.S. Pat. No. 5,942,712 to Mello;        U.S. Pat. No. 5,984,635 to Keller;        U.S. Pat. No. 6,044,746 to Gendre et al;        U.S. Pat. No. 6,079,310 to Yagla et al.;        U.S. Pat. No. 6,230,629 to Doctor et al; and        U.S. Pat. No. 5,302,076 to Bredy.        
Specifically, Jackson et al. discloses a lower power arcjet propellant feed system for delivering propellant to the low power arcjet. The low power arcjet propellant feed system includes a liquid propellant storage chamber for storing a liquid propellant. A gas generator in communication with the liquid propellant storage chamber generates a gaseous propellant upon receipt of the liquid propellant from the liquid propellant storage chamber. A gas plenum in communication with the gas generator accumulates the gaseous propellant for the gas generator up to a desired pressure. Actively controllable valves actively control the flow of the liquid propellant into the gas generator and actively control the flow of the resultant gaseous propellant out of the gas generator and into the gas plenum up to the desired pressure. A substantially continuous and stable low flow rate of gaseous propellant is then delivered to the low power arcjet.
The patent to Yagla et al. '919 discloses a launcher having means for directing and concentrically spreading, as well as dispersing, exhaust gases created by an internal combustion of an object, such as a missile, that is operatively launchable therefrom. The concentric duct provides the directing, spreading and dispersing means and cooperates with a cup having a means to arrange a port in operative relationship with an exhaust outlet of the object being launched. The cup which mates with the concentric duct has one of its ends open to the ambient so that the exhaust gases are lead into and out of the concentric duct so as to be concentrically dispersed into the atmosphere.
Mello discloses a submarine signal launcher for preventing pinched control wires therein. The submarine signal launcher includes a gas generator, an acoustic device countermeasure, a launch tube for housing the gas generator and the countermeasure, and a ram plate positioned between the gas generator and the countermeasure. A status cable is connected to the countermeasure and intermediately threaded through the ram plate and joined to the gas generator. A collapsible tube is connected to the ram plate and the gas generator. The status cable is confined within the collapsible tube. Securing members are formed on opposing ends of the collapsible tube for securing the collapsible tube to the ram plate and the gas generator, wherein upon assembly of the gas generator with the ram plate and the countermeasure within the launch tube, the collapsible tube will protect the cable from being pinched between joined ends of the ram plate and the gas generator.
Keller discloses a helicopter aircraft with an upper hollow center circular plenum in gaseous communication with a plurality of hollow hinged attached rotor blades. Below the plenum and in gaseous communication with it are two fan jet engines whose gaseous output can be inputted to the plenum and their attached hollow rotor blades through an operator controlled valve system. This same valve system can be adjusted to completely or partially by-pass the plenum and discharge the jet engines' gas to a common rear rudder located on the aircraft to provide directional control to the aircraft when in flight. The plenum is shaped lenticular in cross section similar to an airplane wing to provide a lifting body when the helicopter is in forward flight.
The patent to Gendre et al. discloses a projectile propulsion assembly of the type comprising a chamber housing a pressure source. The chamber which houses the pressure source communicates with at least one pipe placed inside the launch tube and having bores distributed along its length so as to be released in succession during ejection of the projectile.
Yagla et al. '310 discloses a launcher having means for directing and concentrically spreading, as well as dispersing, exhaust gases created by an internal combustion of an object, such as a missile, that is operatively launchable therefrom. The concentric duct provides the directing, spreading and dispersing means and cooperates with a cup having means to arrange a port in operative relationship with an exhaust outlet of the object being launched. The cup which mates with the concentric duct has one of its ends open to the ambient so that the exhaust gases are lead into and out of the concentric duct so as to be concentrically dispersed into the atmosphere.
The patent to Doctor et al. discloses an IR radiating decoy for an IR seeking anti-ship missile (ASM) and includes a propulsion section, safe and arming section, gas generator section, fuel tank section, and flight stabilization section to ignite and continuously maintain an IR plume for decoying the ASM away from the targeted ship. The IR radiating decoy ignites the IR plume immediately when the decoy reaches a safe separation distance from the targeted ship. The IR plume continues to be emitted as the decoy flies away, as it lands on the water, and while it floats upon the water until all the fuel is used from the fuel tank. The fuel can be changed to change the signature of the IR plume so that different ASM missiles can be drawn away from the ship.
Bredy discloses a four stroke combustion engine and method of operation of use and control. The engine includes a combustion chamber with an intake manifold coupled to the combustion chamber. A one-way valve is located within the intake manifold. The engine includes an intake valve for modulating the flow of a fuel-air mixture into and out of the combustion chamber. The engine preferably employs a fixed, late closing intake valve. A plenum chamber is located in the intake manifold. The plenum chamber is located downstream of the one-way valve and upstream of the intake valve. During the compression stroke of the engine, a pressurized charge of the fuel-air mixture is stored within the manifold and plenum. The amount of the fuel-air mixture stored within the plenum is controlled by adjusting the volume of the plenum, or, alternatively, a plenum valve is used to regulate the amount of fuel-air mixture entering/exiting a fixed volume plenum.
It should be understood that the present invention would in fact enhance the functionality of the above patents by providing an adjustable volume plenum that reduces peak acceleration on the countermeasure device being launched from the launch tube assembly.